The present invention relates to a thermal spray powder used in applications for forming a thermal sprayed coating by, for example, high-velocity flame spraying, such as high-velocity oxyfuel (HVOF) spraying, or detonation flame spraying.
Cavitation erosion, which is a phenomenon resulting from shock waves and microjets and is generated by the collapse of cavitations corroding a solid surface, is a problem that occurs in fluid devices such as hydraulic turbines or pumps. In situations where the occurrence of cavitation erosion is a cause for concern, conventional measures for tackling this problem included forming the subject part from a material having excellent cavitation erosion resistance or coating the subject part with a material having excellent cavitation erosion resistance. Examples of materials known to have excellent cavitation erosion resistance include cobalt-based alloys, such as a stellite alloy, a martensite stainless steel comprising 13% chrome, and the composite materials disclosed in Japanese Laid-Open Patent Publication No. 8-60278. Examples of coatings known to have excellent cavitation erosion resistance include the coatings disclosed in Japanese Laid-Open Patent Publication Nos. 2001-107833 and 2003-247084.
However, while these conventional techniques can confer good cavitation erosion resistance, in many cases they are unable to confer sufficient resistance to wear caused by hard particles contained in a fluid (i.e. slurry erosion resistance). Furthermore, because the coatings disclosed in Japanese Laid-Open Patent Publication Nos. 2001-107833 and 2003-247084 are formed by either a plasma transfer arc process or by heating to fuse thermally-sprayed self-fluxing alloy coatings, the thermal effects against the substrate cannot be ignored.